The criteria for "worst" is kind of subjective. Let's face it, the coach who follows Satan at Bama who goes 9-3 will be the "worst" ever coach.
I didn't see a mention of Zook who would fall into the "worst" since he took a program that historically achieved high marks and was mediocre.
Mike Riley at Nebraska deserves a mention.
Didn't see Joker Phillips at UK... of course, it's UK and they really didn't have football during his time.
And can't mention Kentucky without Hal Mumme lol
Charlie Strong at Texas never really was able to get anything going (I've always considered him the Derek Dooley of Texas)
Lovie Smith (thankfully his plane is still circling) was a huge hype and complete lackluster performance at Illinois.
Tim Beckman, Art Briles and DJ Durkin all have levels of "worst" in them... going from bad to worst.
I'll get slammed for this, but Kirk Ferentz deserves a mention. Literally at Iowa for two decades in the weak West division and only gets two Big 10 Championships in his tenure?